Autologous hematopoietic cell transplantation for multiple myeloma patients with renal insufficiency: a center for international blood and marrow transplant research analysis.

Autologous hematopoietic cell transplantation (AHCT) in multiple myeloma (MM) patients with renal insufficiency (RI) is controversial. Patients who underwent AHCT for MM between 2008 and 2013 were identified (N=1492) and grouped as normal/mild (⩾60 mL/min), N=1240, moderate (30-59), N=185 and severe RI (<30), N=67 based on Modification of Diet in Renal Disease. Multivariate analyses of non-relapse mortality (NRM), relapse, PFS and overall survival (OS) were performed. Of the 67 patients with severe RI, 35 were on dialysis prior to AHCT. Patients received melphalan 200 mg/m2 (Mel 200) in 92% (normal/mild), 75% (moderate) and 33% (severe) RI; remainder received 140 mg/m2 (Mel 140). Thirty four of 35 patients with severe RI achieved post-AHCT dialysis independence. The 5-year PFS for normal, moderate and severe RI was 35 (95% CI, 31-38)%, 40 (31-49)% and 27 (15-40)%, respectively, (P=0.42); 5-year OS for normal, moderate and severe RI was 68 (65-71)%, 68 (60-76)% and 60 (46-74)%, respectively, (P=0.69). With moderate RI, 5-year PFS for high-dose melphalan 140 mg/m2 was 18 (6-35)% and for Mel 200 was 46 (36-57)% (P=0.009). With severe RI, 5-year PFS Mel 140 was 25 (11-41) % and for Mel 200 was 32 (11-58)% (P=0.37). We conclude that AHCT is safe and effective in patients with MM with RI.

Contribution of chemotherapy mobilization to disease control in multiple myeloma treated with autologous hematopoietic cell transplantation.

In patients with multiple myeloma (MM) undergoing autologous hematopoietic cell transplantation (auto-HCT), peripheral blood progenitor cells may be collected following mobilization with growth factor alone (GF) or cytotoxic chemotherapy plus GF (CC+GF). It is uncertain whether the method of mobilization affects post-transplant outcomes. We compared these mobilization strategies in a retrospective analysis of 968 patients with MM from the Center for International Blood and Marrow Transplant Research database who received an auto-HCT in the US and Canada between 2007 and 2012. The kinetics of neutrophil engraftment (⩾0.5 × 10(9)/L) was similar between groups (13 vs 13 days, P=0.69) while platelet engraftment (⩾20 × 10(9)/L) was slightly faster with CC+GF (19 vs 18 days, P=0.006). Adjusted 3-year PFS was 43% (95% confidence interval (CI) 38-48) in GF and 40% (95% CI 35-45) in CC+GF, P=0.33. Adjusted 3-year OS was 82% (95% CI 78-86) vs 80% (95% CI 75-84), P=0.43 and adjusted 5-year OS was 62% (95% CI 54-68) vs 60% (95% CI 52-67), P=0.76, for GF and CC+GF, respectively. We conclude that MM patients undergoing auto-HCT have similar outcomes irrespective of the method of mobilization and found no evidence that the addition of chemotherapy to mobilization contributes to disease control.

Primary graft failure after myeloablative allogeneic hematopoietic cell transplantation for hematologic malignancies.

Clinical outcomes after primary graft failure (PGF) remain poor. Here we present a large retrospective analysis (n=23,272) which investigates means to prevent PGF and early detection of patients at high risk. In patients with hematologic malignancies, who underwent their first myeloablative allogeneic hematopoietic cell transplantation, PGF was reported in 1278 (5.5%), and there was a marked difference in PGFs using peripheral blood stem cell compared with bone marrow grafts (2.5 vs 7.3%; P<0.001). A fourfold increase of PGF was observed in myeloproliferative disorders compared with acute leukemia (P<0.001). Other risk factors for PGF included recipient age <30, HLA mismatch, male recipients of female donor grafts, ABO incompatibility, busulfan/cyclophosphamide conditioning and cryopreservation. In bone marrow transplants, total nucleated cell doses ⩽2.4 × 10(8) per kg were associated with PGF (odds ratio 1.39; P<0.001). The use of tacrolimus-based immunosuppression and granulocyte colony-stimulating factor were associated with decreased PGF risk. These data, allow clinicians to do more informed choices with respect to graft source, donor selection, conditioning and immunosuppressive regimens to reduce the risk of PGF. Moreover, a novel risk score determined on day 21 post transplant may provide the rationale for an early request for additional hematopoietic stem cells.

Efficacy and safety of hematopoietic stem cell remobilization with plerixafor+G-CSF in adult patients with germ cell tumors.

Autologous hematopoietic SCT (auto-HSCT) can be curative for patients with germ cell tumors. Poor stem cell mobilization jeopardizes the ability to deliver this therapy. Herein, we describe a retrospective study examining safety and efficacy of plerixafor in combination with G-CSF for patients with germ cell tumors who had previously failed stem cell collection. Overall, 21 patients with germ cell tumors and previous mobilization failure were remobilized with G-CSF (10 µg/kg SC) and plerixafor (0.24 mg/kg SC) beginning the evening of day 4 of G-CSF treatment. Dosing of G-CSF and plerixafor was repeated until collection of ≥ 2 × 10(6) CD34+ cells/kg. Remobilization resulted in a median yield of 3.2 × 10(6) CD34+ cells/kg. A total of 17 (81%) patients collected ≥ 2 × 10(6) and 9 (43%) patients collected ≥ 4 × 10(6) CD34+ cells/kg in a median of 2 (range 1-3) and 3 (range 1-4) days, respectively. In all, 16 (76%) patients proceeded to transplant; 8 (38%) received tandem transplants. There were no serious adverse events. In summary, the majority of patients with germ cell tumors who failed prior mobilization with growth factors ± chemotherapy were remobilized with plerixafor plus G-CSF facilitating at least one auto-HSCT. Use of plerixafor plus G-CSF can increase access of this potentially life-saving procedure to patients with high-risk germ cell tumors.

Cyclosporine and mycophenolate mofetil prophylaxis with fludarabine and melphalan conditioning for unrelated donor transplantation: a prospective study of 22 patients with hematologic malignancies.

In an attempt to decrease toxicity in high-risk patients undergoing unrelated donor hematopoietic stem cell transplantation (URD HSCT), we tested a combination of cyclosporine (CSP) and mycophenolate mofetil (MMF) as graft-versus-host disease (GVHD) prophylaxis with the reduced-intensity conditioning regimen fludarabine/melphalan (Flu/Mel). A total of 22 adult patients with advanced myeloid (n=15) and lymphoid (n=7) malignancies were treated. All patients received Flu 25 mg/m2 for 5 days and Mel 140 mg/m2, with CSP 3 mg/kg daily and MMF 15 mg/kg three times a day. The median age was 49 years (range 18-66). Durable engraftment was seen in all but one patient with myelofibrosis. The 1-year nonrelapse mortality was 32%, 27% from GVHD. The cumulative incidence of acute GVHD grade 2-4 and 3-4 was 63 and 41%, respectively. With a median follow-up of 18 months, the disease-free survival (DFS) and overall survival (OS) are 55 and 59%, respectively. For patients with AML and MDS (n=14), the DFS and OS is 71%. For patients undergoing a second transplant (n=14), the DFS and OS is 57%. In conclusion, this regimen is associated with acceptable toxicity but high rates of GVHD in high-risk patients undergoing URD HSCT. Encouraging disease control for patients with advanced myeloid malignancies was observed.

High-dose paclitaxel in combination with doxorubicin, cyclophosphamide and peripheral blood progenitor cell rescue in patients with high-risk primary and responding metastatic breast carcinoma: toxicity profile, relationship to paclitaxel pharmacokinetics and short-term outcome.

We assessed the feasibility and pharmacokinetics of high-dose infusional paclitaxel in combination with doxorubicin, cyclophosphamide, and peripheral blood progenitor cell rescue. Between October 1995 and June 1998, 63 patients with high-risk primary [stage II with >or= 10 axillary nodes involved, stage IIIA or stage IIIB inflammatory carcinoma (n = 53)] or with stage IV responsive breast cancer (n = 10) received paclitaxel 150-775 mg/m(2)infused over 24 hours, doxorubicin 165 mg/m(2)as a continuous infusion over 96 hours, and cyclophosphamide 100 mg kg(-1). There were no treatment-related deaths. Dose-limiting toxicity was reversible, predominantly sensory neuropathy following administration of paclitaxel at the 775 mg/m(2) dose level. Paclitaxel pharmacokinetics were non-linear at higher dose levels; higher paclitaxel dose level, AUC, and peak concentrations were associated with increased incidence of paraesthesias. No correlation between stomatitis, haematopoietic toxicities, and paclitaxel dose or pharmacokinetics was found. Kaplan-Meier estimates of 30-month event-free and overall survival for patients with primary breast carcinoma are 65% (95% CI; 51-83%) and 77% (95% CI; 64-93%). Paclitaxel up to 725 mg/m(2) infused over 24 hours in combination with with doxorubicin 165 mg/m(2) and cyclophosphamide 100 mg kg(-1) is tolerable. A randomized study testing this regimen against high-dose carboplatin, thiotepa and cyclophosphamide (STAMP V) is currently ongoing.

Retrospective multivariate analysis of hepatic veno-occlusive disease after blood or marrow transplantation: possible beneficial use of low molecular weight heparin.

This retrospective cohort study of 462 consecutive adult allogeneic and autologous blood or marrow transplantation (BMT) patients compared the incidence of hepatic veno-occlusive disease (VOD) after BMT with three prophylactic regimens. Patients receiving heparin (Hep), heparin + prostaglandin E1 (Hep + PGE1) or low molecular weight heparin (LMWH) as a prophylactic VOD regimen were compared to a historical cohort receiving no VOD prophylaxis. Of 462 BMT patients, VOD was diagnosed in 22% (31 of 142) of the no prophylaxis group, 11% (11 of 104) of the Hep, 12% (13 of 110) in the Hep + PGE1 and 4% (four of 106) of the LMWH group (P = 0.0002). VOD was the primary cause of death in 20% (12 of 59). By multivariate logistic regression, independent risk factors for developing VOD were: no VOD prophylactic regimen, unrelated allogeneic BMT, Karnofsky performance score (KPS) < 80 and aspartate aminotransferase (AST) > or =50 U/l. There was no increase in the rate of death due to hemorrhagic events or VOD in any prophylaxis group compared to the control group. Prospective randomized trials of Hep vs LMWH vs placebo are warranted to assess the efficacy of heparin compounds in the prevention of VOD.

Phase II trial of high-dose intravenous doxorubicin, etoposide, and cyclophosphamide with autologous stem cell support in patients with residual or responding recurrent ovarian cancer.

This study was performed in order to evaluate the toxicities, progression-free and overall survival of patients with responsive residual or recurrent ovarian cancer treated with high-dose chemotherapy. Twenty-seven patients were treated. Doxorubicin, 165 mg/m(2) over 96 h (days -12 to -8), etoposide 700 mg/m(2) every day x3 (days -6 to -4), and cyclophosphamide 4.2 g/m(2) on d -3 was followed by stem cells and granulocyte colony-stimulating factor. The median days of granulocyte count <500/microl was 14 (range 10-42) and platelets <20,000/microl was 13 (range 2-80). Median numbers of red cell and platelet transfusions were 15 (5-16) and 14 (4-103). Toxicity included mucositis requiring narcotic analgesia in all patients. Asymptomatic decreases in ejection fraction to values <50% were observed in four patients. No clinical congestive heart failure was observed. One death due to sepsis was observed. Median progression-free survival is 7.5 months (1.0-56 months); five patients remain alive, two of whom remain progression-free at 19.5 and 24.5 months post transplant. Median overall survival is 14.0 months (1-68 months). We conclude that high-dose anthracyclines may be safely administered to ovarian cancer patients. The short overall and progression-free survivals observed in our population suggest that this combination is not optimal.

High-dose therapy with hematopoietic cell transplantation for patients with central nervous system involvement by non-Hodgkin's lymphoma.

Central nervous system (CNS) involvement by non-Hodgkin's lymphoma (NHL) carries a poor patient prognosis whether it occurs as a primary site of disease or secondarily in patients with systemic disease. In a group of 481 patients undergoing high-dose therapy with hematopoietic cell transplantation (HCT) for NHL, 15 patients (3.1%) were identified with CNS involvement. Two patients had primary CNS lymphoma, and 13 had secondary disease. All patients received intrathecal chemotherapy, and 13 received CNS radiotherapy before transplantation. Fourteen patients received systemic chemotherapy. At the time of transplantation, both patients with primary CNS lymphoma and 8 patients with secondary disease had achieved a complete response, 3 patients had achieved a partial response, 1 had failed induction therapy, and 1 had progression of CNS disease before high-dose therapy. Fourteen patients received carmustine, etoposide, and cyclophosphamide as the preparative regimen, and 1 patient received fractionated total body irradiation instead of carmustine. The 2 patients with primary CNS lymphoma were alive and free of disease, 1 at 1,085 days after HCT and 1 at 3,704 days after HCT. The actuarial 5-year event-free survival (EFS) was 46% +/- 26%, and overall survival (OS) was 41% +/- 28%. The median EFS and OS were 2.2 and 1.5 years, respectively. Three patients experienced symptomatic memory loss or intellectual decline after therapy, 1 patient developed paraplegia, and 1 patient had a thrombotic stroke 20 months after HCT. Despite treatment-related toxicities, 7 patients responding to quality-of-life questions at approximately 1 year after HCT gave their overall quality of life a median rating of 9 out of a possible 10 (range, 6-10). High-dose therapy with autologous HCT can produce extended EFS in patients with secondary CNS lymphoma and possibly in those with primary CNS NHL.

Tissue plasminogen activator (tPA) as therapy for hepatotoxicity following bone marrow transplantation.

The treatment of established veno-occlusive disease (VOD) of the liver with tissue plasminogen activator (tPA) has been disappointing. In attempts to improve upon these results we identified a subgroup of patients with consistently elevated bilirubin levels who did not meet conventional criteria for VOD (Susp VOD) but who had a significant risk of later developing clinical VOD. In January 1994 we began to treat patients who developed Susp VOD with tPA rather than waiting until they developed clinical VOD. We now report on the results of the first 37 patients who ultimately developed clinical VOD and received tPA therapy prior to Susp VOD, or at the time they had established VOD. Significant bleeding complications occurred in 13 (35%) patients but resolved with discontinuation of therapy in all but one. We found that patients treated early in the course of hepatotoxicity prior to the development of overt VOD had a significantly higher response rate and 100 day survival than patients treated at the time of established VOD. Given the poor results seen in treating late VOD, we suggest that early treatment with tPA may improve the outcome in patients who develop signs of hepatotoxicity following marrow transplantation.

Interferon-alpha-associated focal segmental glomerulosclerosis with massive proteinuria in patients with chronic myeloid leukemia following high dose chemotherapy.

BACKGROUND: Acute renal failure, with or without massive proteinuria, is a rare idiosyncratic toxicity of interferon (IFN)-alpha therapy. The authors sought to review their experience with this toxicity as well as the world literature on the subject. METHODS: The authors describe two patients with chronic myeloid leukemia treated with IFN-alpha following high dose chemotherapy who developed renal failure and proteinuria after 3 and 4 weeks of IFN-alpha therapy, respectively. Fifteen previously reported cases of renal failure and proteinuria associated with IFN-alpha therapy are also reviewed. RESULTS: Renal biopsies performed on the authors' two patients revealed focal segmental glomerulosclerosis. However, the other reported patients with IFN-alpha-associated renal failure and massive proteinuria had an assortment of pathologic findings. CONCLUSIONS: The specific renal pathology associated with proteinuria may be a consequence of the condition and not its cause; differences in renal pathology may be caused by other predisposing factors. Patients treated with IFN-alpha following high dose chemotherapy, with or without autologous transplantation, should be followed for the development of proteinuria and renal failure.

The effect of human leukocyte antigen disparity on cyclosporine neurotoxicity after allogeneic bone marrow transplantation.

PURPOSE: We examined the relationship between human leukocyte antigen (HLA) matching and the development of cyclosporine (CyA) neurotoxicity in patients undergoing allogeneic bone marrow transplantation, and determined the frequency and imaging characteristics of CyA neurotoxicity in these patients. METHODS: Records of 87 patients who underwent allogeneic bone marrow transplantation were reviewed. Eight patients who presented with visual disturbance and/or seizures and had MR imaging within 24 hours were identified. Transplant donor relatedness was examined, and patients' imaging studies were reviewed. Clinical parameters, including blood pressure, CyA, creatinine, and magnesium levels, and the presence of graft-versus-host disease were reviewed. RESULTS: CyA neurotoxicity was seen more frequently in HLA-mismatched and unrelated donor transplants. The frequency of CyA neurotoxicity was 4% for patients with a 5/6 or 6/6 HLA match, 13% for matched unrelated donor transplants, and 50% for haplotypic 3/6 or 4/6 transplants. Patients with matched unrelated donor transplants and haplotypic transplants presented earlier in the posttransplant time course and had decreased survival time relative to patients with HLA-matched transplants. Imaging abnormalities most commonly affected the occipital lobes and the posterior cerebral hemispheres; both cortical and white matter involvement was identifiable as T1 hypointense and T2 hyperintense signal with associated gyral swelling and sulcal effacement on the initial MR studies. Hypodensity in the affected areas was noted on CT scans. Contrast enhancement was seen in HLA-mismatched and unrelated transplants only. Follow-up imaging showed interval decreases in subcortical edema; however, residual signal abnormality, primarily affecting the cortex, was present in all cases and seen best on proton density-weighted MR images. CONCLUSION: The frequency of severe CyA neurotoxicity increases with increasing HLA disparity, suggesting that immune factors may play a role. CyA neurotoxicity appears to represent a spectrum of disease processes. Disruption of the blood-brain barrier as well as hypoxic or vasculitic cortical injury resulting in MR-detectable cortical signal abnormalities may occur in severe cases.

Severe cerebellar swelling and thrombotic thrombocytopenic purpura associated with FK506.

Two patients with CsA-associated neurotoxicity developed severe cerebellar swelling and thrombotic thrombocytopenic purpura after switching to FK506 and high-dose corticosteroids. The prodrome of CsA-associated neurotoxicity, TTP and hypertension while receiving FK506, and high-dose corticosteroids could all be implicated in the development of this syndrome. Close monitoring of patients receiving FK506 and high-dose corticosteroids, for the development of TTP is warranted. Early radiological examination should also be considered in such patients to allow early surgical intervention.

Characterization of interleukin-10 receptor expression on B-cell chronic lymphocytic leukemia cells.

B-cell chronic lymphocytic leukemia (B-CLL) cells accumulate in vivo in the G0/G1 phase of the cell cycle, suggesting that their malignant expansion is due, at least in part, to a delay in cell death. However, the cellular or molecular factors responsible for a delay in B-CLL cell death are unknown. B-CLL cells do express receptors for interferon-alpha (IFN-alpha) and IFN-gamma, and activation of both has been shown to promote B-CLL survival in vitro by preventing apoptosis. The interleukin-10 (IL-10) receptor is another member of the IFN receptor family, but its ligand, IL-10, has been reported to induce apoptosis in B-CLL cells. In the current study, we undertook a biochemical analysis of IL-10 receptor expression on freshly isolated B-CLL cells and characterized the functional responsiveness of IL-10 binding to its constitutively expressed receptor. We show that B-CLL cells bind IL-10 with significant specificity and express between 47 and 127 IL-10 receptor sites per cell, with a dissociation constant in the range of 168 to 426 x 10(-12) mol/L. Ligand binding and activation of the IL-10 receptor expressed on B-CLL cells results in the phosphorylation of signal transducer and activator of transcription 1 (STAT1) and STAT3 proteins. This pattern of STAT protein phosphorylation is identical to IL-10 receptor activation on normal cells and similar to IFN-alpha (STAT1 and STAT3) and IFN-gamma (STAT1) receptor activation in CLL. Further, in consecutive samples of fresh blood obtained from patients with B-CLL cells, the addition of IL-10 inhibited B-CLL proliferation, enhanced B-CLL differentiation, but did not induce apoptosis. Indeed, IL-10, like IFN-gamma, was able to significantly reduce the amount of B-CLL cell death caused by hydrocortisone-induced apoptosis. We conclude that cytokines, which signal through the interferon family of receptors, have comparable functional effects on B-CLL cells.

Influence of age on the outcome of 500 autologous bone marrow transplant procedures for hematologic malignancies.

PURPOSE: To determine the effect of age on the outcome of autologous bone marrow transplantation (ABMT) and/or peripheral-blood progenitor-cell (PBPC) transplantation. PATIENTS AND METHODS: A retrospective analysis was performed on 500 consecutive patients who ranged in age from 1 to 65 years (median, 40) with non-Hodgkin's lymphoma (NHL), Hodgkin's disease (HD), multiple myeloma (MM), or acute nonlymphoblastic leukemia (AML) who underwent autologous hematopoietic-cell transplant procedures at Stanford University Medical Center. RESULTS: The actuarial 5-year event-free survival (EFS) rate was 44%, the relapse rate 47%, and the regimen-related mortality (RRM) rate 8.6%. Disease status at time of transplantation, categorized as either minimal or advanced disease, was the strongest predictive factor for EFS (relative risk (RR) for advanced-disease group, 1.8; P < .0003) and relapse rate (RR for advanced-disease group, 1.9; P < .0004). Patients with minimal or advanced disease had an EFS rate of 48% and 30% and relapse rates of 43% and 72%, respectively. The EFS rate of patients less than 50 years verus > or = 50 years of age was 46% versus 34% (P = .03). Cox regression analysis showed that age was predictive for EFS (RR for patients 50 to 65 years, 1.4; P = .03). The actuarial RRM rate for these age groups was 7.4% versus 12.7% (P = .07), respectively. Multivariate analysis demonstrated that age (odds ratio [OR] for patients 50 to 65 years, 1.9; P < .05) and period of transplantation (OR for most recent years [1991 to 1995], 0.6; P = .06) were the most predictive factors for RRM. CONCLUSION: Although age greater than 50 years is associated with an inferior outcome following autologous hematopoietic-cell transplantation, it does not appear to be warranted to limit this potentially curative procedure based solely on age. The upper age limit of high-dose therapy with autologous progenitor-cell and/ or bone marrow support remains to be defined.

Multiple cycles of high dose chemotherapy supported by hematopoietic progenitor cells as treatment for patients with advanced malignancies.

BACKGROUND: Retrospective studies suggest that dose intensity is an important determinant of outcome in the treatment of patients with a variety of malignant diseases such as breast cancer, ovarian cancer, and lymphoma. Unfortunately, these results have not been clearly substantiated in prospective randomized trials. One problem with these studies may be that the degree of dose escalation is not sufficient to result in an improved outcome because the chemotherapy doses are limited by hematopoietic toxicity. In an attempt to deliver more dose-intensive therapy, the feasibility of the administration of multiple cycles of high dose chemotherapy with hematopoietic progenitor cell and growth factor support was investigated in patients with advanced malignancies. METHODS: Nineteen patients with metastatic breast cancer and six patients with refractory non-Hodgkin's lymphoma were initially treated with etoposide (VP-16) (2 gm/m2) and granulocyte-colony stimulating factor (G-CSF). Peripheral blood hematopoietic progenitor cells were collected by leukapheresis and cryopreserved as the patients' leukocyte counts recovered from the nadir induced by VP-16. Patients were then treated with four cycles of mitoxantrone (18 mg/m2), thiotepa (150-200 mg/m2) and cyclophosphamide (4500-5000 mg/m2) as a 48-72 hour continuous infusion followed by infusion of one-quarter of their progenitor cells 48 hours later. All patients also received G-CSF (5 micrograms/kg/day) until engraftment. RESULTS: A total of 88 of a planned 100 cycles of therapy were administered to these 25 patients. The median time to recovery of an absolute neutrophil count of 500/microliters or greater was 13-14 days (range, 7-18 days) and time to recovery of a platelet count of 20,000/microliters or greater was 13-14 days (range, 7-16 days) after the initiation of each cycle of chemotherapy. The median number of platelet transfusions required after each cycle was 2-3 (range, 0-18 transfusions) and the number of erythrocyte transfusions was 4 (range, 0-10). The most common toxicity was diarrhea. Prophylactic intravenous antibiotics were administered to avoid fever with neutropenia. Two patients developed interstitial pneumonitis and one patient died. One heavily pretreated patient failed to engraft after the first cycle. Reversible veno-occlusive disease of the liver developed in one patient after the fourth cycle of therapy. Four patients progressed while on therapy. Eight patients were disease free and 13 patients had a partial response or had a positive bone scan as the only evidence of disease at the completion of therapy. Seven patients, two with lymphoma and five with breast cancer (28%), remain progression free with a median follow-up of 24.7 months (range, 17-28 months). CONCLUSIONS: Support with hematopoietic progenitor cells and growth factors allows the timely administration of repetitive cycles of high dose chemotherapy, resulting in a significant increase in dose intensity with acceptable toxicity.